THE next figures are taken from Baldwin Latham's "Sanitary Engineering" and show sediment traps used for Street Gullies. These traps ought to gradually disappear from use and will do so as soon as communities see the importance of building good sewers and properly ventilating them. The street sewer inlets will then serve as sewer inlet vents and the traps will be done away with. The silt-basins must also disappear with the disuse of horses. Automobiles will require perfectly smooth pavements, which are not entirely without drawbacks now, on account of the danger to horses from slipping. These smooth pavements will then be kept perfectly clean and the ventilating openings into the sewers will be very simple and inexpensive.

Until such time, however, street gullies and sediment traps will be used, and the drawings show the principle upon which they are constructed.

"Gullies are liable to fail in times of frost, especially in very cold countries, as the gullies and traps get completely frozen up, and, when a sudden thaw takes place, they are found locked up with ice, so that the water cannot readily escape, and the streets, in consequence, get flooded. The remedy for this is to remove the water in the gully as far as possible from, the surface, and the gullies are constructed with special reference to the breaking up of the ice in the traps should it accumulate. Figure no represents the section of a street gully which has been used at Carlsruhe, Germany. The gully is made in two portions, with a trap in the division wall. Should the trap get frozen, the stone S is removed from that portion into which the trap discharges, and a suitable tool may be inserted to break up the ice. * * * In all cases gullies are liable to become untrapped from leakage or from evaporation, therefore, to insure the integrity of the traps, they should have the water constantly renewed in dry weather. * * * All gullies should be regularly scavenged, not less frequently than once every six or ten days, as matters are often passed into them, which decay and give off an offensive effluvium if left too long in the gully. * * * Gullies are usually provided with grated coverings * * * which should be arranged at right angles to the traffic, or otherwise narrow-wheeled vehides are liable to get injured in the openings between the bars of the gratings.*

Street Gullies And Siphonable Traps 119

Fig. 107.

Street Gullies And Siphonable Traps 120

Fig. 106.

Street Gullies And Siphonable Traps 121

Fig. 108.

Street Gullies And Siphonable Traps 122

Fig. 109.

Street Gullies And Siphonable Traps 123

Fig. 110.

Street Gullies And Siphonable Traps 124

Fig. 111.

Fie. 112.

Fie. 112.

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Fig. 113.

Figure 106 is a representation of a gully trap which is an improvement upon the common Bell trap, the bell not being attached to the cover, but being loose, and having a perforated bottom and dropping down on the center cone D. The top grating is hinged and can be raised so that the trap can be easily cleaned out. B is the level of the street surface, and C of the water. The arrows indicate the direction of the passage of the water to the drains.

Figure 107 is a London gully-hole with a cesspool constructed under the sidewalk in order to facilitate its cleansing in narrow streets of great traffic. The solid matter is collected in the bottom of the cesspool and removed from time to time through the stone manhole in the sidewalk.

Figure 108 is a larger gully with cesspool under the sidewalk. It contains room for a large amount of road detritus to be periodically moved as described for Fig. 107. Fig. 109 is a street gully with earthenware trap. The gully itself is made of concrete in one piece, strengthened with wrought iron bands cast within the concrete. This construction has been used in the city of Dantzic where the climate is very severe.

Figures 111 and 112 are gully traps suitable for yards, but the curved bottom of the latter with the outlet near it, renders it liable to transmit detritus into the sewers where a large volume of water passes through it.

Figure 113 shows a double trap London street gully, the smaller catch-pit is not so easily evaporated out as the larger one, which is more exposed, and the emptying of the larger one still leaves the gully trapped.

Figures 114 and 115 show a cast-iron gully having several good points where traps are desired at all. First it has a trap which is as reliable as possible at all times, the usual traps losing their seals when the level of the water is reduced by the removal of deposits. Second, very little evaporation goes on in summer, and freezing in winter is impeded. Third, there is ample space for road detritus.. Fourth, it has a flushing aperture in the small trap. Fifth, it is economical and requires no brickwork in setting.

*Baldwin Latham.

Figs. 114 and 115.

Figs. 114 and 115.

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Fig. 116.

Street Gullies And Siphonable Traps 129